1. Technical Field
The present invention relates to a technique of compensating for error of characteristics (more particularly, threshold voltage) of a transistor within an electronic circuit.
2. Related Art
In JP-A-2009-48202, a technique of compensating for error of characteristics (threshold voltage or mobility) of a driving transistor used for driving an organic EL element is disclosed. FIG. 43 is a circuit diagram of a pixel circuit 90 disclosed in JP-A-2009-48202 (FIG. 11). In a write period in which a gradation potential according to a designated gradation is supplied to an electrode 93 of a capacitive element 92 through a switch 91, a gate and a drain are connected (diode-connected) to a switch 95 in a state in which a driving transistor 94 is held in an on state. Accordingly, a voltage between the gate and the source of the driving transistor 94 is set to a voltage Vrst for compensating for error of its threshold voltage VTH. A driving potential having a triangular wave shape is supplied to the electrode 93 of the pixel circuit 90 in a driving period after the elapse of the write period so as to variably control a light emission time of a light emitting element 97 connected to a circuit point 96 according to the designated gradation.
However, it is difficult to apply the technique of JP-A-2009-48202 to a configuration in which an electro-optical element having high resistance, such as an electrophoretic element or a liquid crystal element, is connected to the circuit point 96. Since current barely flows in the electro-optical element, the potential of the circuit point 96 is not set. Accordingly, even when the driving transistor 94 and the switch 95 are controlled to the on state in the write period, the voltage between the gate and the source of the driving transistor 94 does not converge to a target voltage Vrst.